Blade for rotary blowers and compressors



May 20, 1930.

v w. VAN RIJSWIJK BLADE FOR ROTARY BLOWERS AND COMPRESSORS Filed Aug. 22, 1927 Patented May 20, 1930 v,

UNITED STATES PATENT0FFICE:

VIILLIEM VAN RIJSWIJK, 0F BADEN, SWITZERLAND, lASSlG'rNOR TO AKTIENGESELL- SCHAFT :BROWN BOVERI & CIE., OF BADEN, SWITZERLAND, A JOINT-STOCK COM- PANY 0F SWITZERLAND BLADE nony ROTARY BLoWERs AND conranssons Application led August 22, 1927, Serial No. 214,597, and in Germany August 25, 1,926.

This invention relates to blowers, compressors, pumps and the like, of the rotary type in which the fluid is impelled by centrifugal force imparted by revolving blades. It has to do particularly with the construction of blades for such machines of large size adapted for operation at high speeds, wherein the rotating parts are subjected to high stresses from centrifugal force and from reaction from the handled fiuid.

The general object of the invention is the provision of a blade construction whereby the weight of the rotating parts will be materially reduced, so as to reduce the centrifugal stresses on the shroud discs and shaft, and a proper strength maintained in the blades andV in their connections to the shroud discs to withstand the pressures of the handled fluids. The ultimate object attained thereby is the possibility of constructing the blowers in large sizes and operating them at increased speeds, without unduly increasing the weight of the shroud discs and the diameter and length of the shaft.

Another object is the provision of a construction whereby these results may be at-V In the drawing forming a part of this specication, I illustrate one form in which the invention may be embodied, but it is to be understood that this is presented by wayof example only, as the invention which it is my purpose to secure under the appended claims is not limited to this particular construction. In said drawing:

Fig. 1 is a perspective view, with a portion in section, of an impeller blade embodying the invention and Fig. 2 is a fragmentary sectional view illustrating the assembly of the impeller blade with the shroud discs.

. In the designing of blades for centrifugal vcompressors to work with high peripheral speeds, it is difficult to obtain the necessary strength in the blades, particularly when they are of considerable width, without subjecting the shroud discs, shaft, and the blade connections, to undesirably heavy centrifugal forces resulting from the weight of the blades. The blades must possess a high degree of strength and stiffness transversely in order to prevent their bending on longitudinal lines under the heavy pressures reacting from the operation of the blades on the handled fluid, and for the same reason, the connections of the blades to the shroud discsmust be very strong. 4

Bythe present invention, which is in the nature of a specific improvement on lconstructions illustrated in United States patent to Meyer No. 1,600,690, one is ableV to obtain strength in the blades by the use of high tensile steel with liberal dimensions for jointing contact between theedges of the blades-and the faces of the shroud discsand also in the connecting means, without involving a commensurate increase in the weight of the blades. The nature of the improvement is illustrated inthe accompanying drawing.- In this the reference'numeral 10 designates an impeller blade,- and 11 the shroud discs `to which it is connected. The blade-is formed in the desired shape and size and thenA drilled transversely to afford the lightening channels 12 which are separated by transverse septa 14 of the metal. In this fashion the total Weight of the blade lmay be reduced in a very material proportion without materiallyreducing the stren th or stiffness of the blade transversely. ence the blade may 'be constructed in the first instance with a substantial thickness so as to afford liberal bearing area between its edges and the faces of the shroud discs. At its margins the blade is provided A with the rivets 16 which may be formed integrally of the blade material, and in order that these rivets may be of liberal size, eX- ceeding in diameter the width of the septa, the channels opposite the rivets may be terminated short of the blade edge to leave the portions of metal 15 as supports for vthe rivets.

In order that the rivets on the two edges of the blade may be arranged in opposite relationship, the channels 12 are drilled in diagonal directions, as illustrated.

It Will, therefore, be seen that in the present improved construction the blade is provided With adjacent passages extending obliquely with respect to the longitudinal axis 17 of the blade, each of such passages being open at one end and closed at the other end by the material of the blade, the closed ends of such passages being disposed at opposite edges of the blade. Such construction or arrangement permits of placement of the bladeretaining elements or rivets 16 adjacent the closed ends of such passages, as shown, the rivets being in alignment in a direction transverse to the blade and disposed on the imaginary line 18 perpendicular to the longitudinal axis 17. Such alignment of the retaining rivets 16 provides for economies in manufacture and for better' distribution of the bladeretaining forces.

When the blades are mounted, the rivets are inserted through holes in the shroud discs and riveted down to draw them closely against the edges of the blade. The blades thus form beam-like connections between the shroud discs which, because of the permissible thickness of the blades, is very strong and stiif transversely. Atthe same time, because of the lightness of the blades, it is not necessary to make the shroud discs undesirably heavy in order to sustain the centrifugal forces.

I claim:

In blading construction for rotary iuid machines, an elongated blade, said blade being provided With adjacent passages extending obliquely with respect to its longitudinal axis and each being open at one end and closed at the other end by the material of said blade, the closed ends of said passages being disposed at opposite edges of said blade, and

- blade-retaining elements associated With said blade and disposed respectively adjacent the closed ends of said passages and substantially on an imaginary line perpendicular to the longitudinal axis of said blade.

In testimony whereof I have hereunto subscribed my name at Zurich, Switzerland, this p 4th day of August, A. D. 1927.

WILLEM VAN RIJSVIJK. 

